Solid state lighting has been developed to overcome some of the problems of incandescent lamps and gas discharge lamps. Solid state lighting (SSL) refers to a type of lighting that utilizes light-emitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments or gas. The term “solid state” refers to the fact that light in an LED is emitted from a solid object—a block of semiconductor—rather than from a vacuum or gas tube, as is the case in traditional incandescent light bulbs and fluorescent lamps. The LED is a semiconductor diode that emits incoherent narrow-spectrum light when electrically biased in the forward direction of the p-n junction, as in the common LED circuit resulting in electroluminescence. Its solid-state nature provides for greater resistance of LED lighting to shock, vibration, and wear, thereby increasing its lifespan significantly.
Many conventional LED devices, however, are limited by thermal energy-management issues. For example, LEDs exhibit negative temperature coefficient aspects. That is, at a fixed power input, as the LED device's operating heat rises, the LED device's light output decreases. High heat during use can shorten the useful life of an LED. It is, however, desirable to run LEDs using high current, because the higher the current, the higher the brightness of the emitted light. Ideally, the temperature measured at the LED leads is a maximum of 120-130 C. Accordingly, there is motivation to manage heat as much as possible in order to operate an LED optimally with regard to power input and light output and LED life.
Form factor standards have been established for lighting fixtures and typically it is desirable to design lamps that conform to the standards. Accordingly, LED lamps are typically required to conform to established size standards including size standards established for other lighting types such as incandescent lamps. The size standards often limit heat management solutions for LED lamps.
It remains desirable to have an LED illumination device wherein heat is managed such that lumens, energy consumption and lifespan are maximized preferably in a form factor conforming to an established standard.